Illuminative light communication device and lighting device

ABSTRACT

In the case of performing communication by using illumination light when the illumination is on, switches are turned on, a signal modulated in an optical modulation part in accordance with information is superposed to a power waveform for the illumination with a power distributor and the illumination  16  is driven in a modulated state. When the illumination is off, the switches are turned off, a switch is turned on and a communication part is driven in a modulated state by the optical modulation part. The communication part can be constituted so as to include an infrared light emitting element part to perform infrared communication when the illumination is off. Consequently communication can be performed not only when the of illumination is on but also when the lighting is kept off. The communication device can be constituted of one element integrating the illumination part and the communication part, so that a compact system can be constituted.

CROSS-REFERENCES TO RELATED APPLICATIONS

This application is a continuation of U.S. patent application Ser. No.10/532,250 filed Oct. 23, 2003, as International Application No.PCT/JP03/013539, now pending, the contents of which, includingspecification, claims and drawings, are incorporated herein by referencein their entirety. This application claims priority from Japanese PatentApplication Serial No. 2003-070673 filed Mar. 14, 2003, the contents ofwhich are incorporated herein by reference in their entireties.

BACKGROUND OF THE INVENTION

The present invention aims to provide an illuminative lightcommunication device, which allows communication even without lightingand effectively utilizes infrared light data communication, and alighting device preferable for such illuminative light communicationdevice.

According to such objective, the illuminative light communication deviceincludes a lighting unit that emits light for lighting, a modulator thatcontrols blinking or light intensity of the lighting unit in accordancewith data, thereby modulating the emitted light, a communicating unitthat transmits the data through optical communication other thanilluminative light communication, and a switch that changes overrespective operations of the modulator and the communicating unit basedon whether the lighting unit is on or off. The switch changes over suchthat the communicating unit can operate while the lighting unit is off.The communicating unit may be structured so as to transmit data throughinfrared light data communication.

As described above, in addition to illuminative light communication thatis made possible by the lighting unit outputting illuminative lightmodulated by the modulator, illuminative light communication is carriedout while the lighting unit is on, using a conventional communicationunit such as infrared light communication unit. On the other hand,without lighting, communication is carried out using a communicationunit such as infrared light data communication. This allows continuouscommunication even without lighting.

Note that when carrying out infrared light data communication, aninfrared light emitting device that can selectively emit infrared lightcan be included in multiple LED devices in the lighting unit. As aresult, it is unnecessary to separately provide another communicatingunit to be used without lighting, and an indoor lighting unit that isdeployed so as to prevent generation of a shadow can be used forinfrared light data communication. This allows reduction in influencesof shadowing, and stable infrared light data communication.

An illuminative light communication device includes a lighting unit thatemits light for lighting and a modulator that controls blinking or lightintensity of the lighting unit in accordance with data, therebymodulating the emitted light. In response to an on-switchinginstruction, the modulator modulates in accordance with the data whilesupplying sufficient electric power for lighting to the lighting unitwhile in response to an off-switching instruction, the modulatormodulates in accordance with the data to allow the lighting unit toblink a number of times necessary for communication.

This structure allows communication with lighting with sufficient lightintensity for lighting, and communication using emitted light onlyrequired for the communication when light intensity is unnecessary orwithout lighting. As a result, users can turn the lighting either on oroff, and optical communication is possible even without lighting.

Furthermore, a lighting device for emitting illuminative light includesan illuminative light emitting device that emits white light forlighting and an infrared light emitting device that emits infrared lightfor infrared data communication. The illuminative light emitting devicecan be controlled for modulation to carry out illuminative lightcommunication independently of the infrared light emitting device. Thisallows illuminative light communication with lighting by illuminativelight emitted from the illuminative light emitting device, and infraredlight data communication without lighting by infrared light emitted fromthe infrared light emitting device. As a result, communication ispossible even without lighting, although communication could not becarried out through conventional illuminative light communicationwithout lighting. In addition, an additional communicating unit is notneeded for infrared light data communication, influences of shadowingcan be reduced and stable infrared light data communication can becarried out, thereby increasing the possibility of infrared light datacommunication.

Note that the lighting device can be structured of a red, a blue, and agreen light emitting device in line with the infrared light emittingdevices. Alternatively, it may be structured of infrared light emittingdevices in line with illuminative light emitting devices, which are madeup of a blue or an ultraviolet light emitting device and fluorescerprovided surrounding the light emitting devices.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a block diagram of an illuminative light communication device,according to a first embodiment of the present invention;

FIG. 2 is a table describing exemplary operations defined according torespective combinations of an ON and an OFF status of switches 12through 14;

FIG. 3 is a schematic diagram of an exemplary lighting element,according to the present invention, which is preferable to being usedfor the illuminative light communication device, according to thepresent invention;

FIG. 4 is a diagram describing an application of an exemplary lightingelement, according to the present invention, to the illuminative lightcommunication device, according to the present invention;

FIG. 5 is a schematic diagram of another exemplary lighting element,according to the present invention, which is preferable to being usedfor the illuminative light communication device, according to thepresent invention;

FIG. 6 is a diagram describing another application of an exemplarylighting element, according to the present invention, to theilluminative light communication device, according to the presentinvention;

FIG. 7 is a block diagram of an illuminative light communication device,according to a second embodiment of the present invention; and

FIGS. 8A-8B each is a diagram of an exemplary structure of a typicalwhite LED; FIG. 8A shows an exemplary structure using three color lightemitting elements; and FIG. 8B shows an exemplary structure usingfluorescer.

DETAILED DESCRIPTION OF THE INVENTION

FIG. 8 is a diagram of a configuration of an exemplary typical whiteLED. In the drawing, 331 and 341 denote LED devices, 332 denotes a redlight emitting element, 333 denotes a green light emitting element, 334denotes a blue light emitting element, 342 denotes a light emittingelement, and 343 denotes fluorescer. An exemplary white LED shown inFIG. 8A is configured such that the red light emitting element 332, thegreen light emitting element 333, and the blue light emitting element334 are arranged in the LED device 331. White light can be seen whenred, green, and blue light emitted from respective light emittingelements are mixed.

In the case of an exemplary white LED shown in FIG. 8B, a blue or anultraviolet light emitting element 342 is provided in the LED device341, and the fluorescer 343 is provided surrounding the light emittingelement 342. As with a fluorescent lamp, the LED device 341 has thefluorescer 343, which emits white light when blue light or ultravioletlight emitted from the light emitting element 342 is irradiated on thefluorescer 343. As a result, white light is emitted.

Since such single LED device has less light intensity for lighting, anLED array made up of multiple LED devices is typically used. In thefollowing description, the LED array may be referred to as just LED.Such LED array is used for some traffic control signals, rear lamps ofan automobile, desk lamps, and foot lights, for example. The features ofLEDs are longer life, smaller size, and lower power consumption thanthose of conventional illuminative light sources such as incandescentlamps and fluorescent lamps. Accordingly use of LEDs as a futureilluminative light source is considered.

In addition, another feature of light emitting elements such as LEDs isa very fast response speed since a preheating time is unnecessary.Paying attention to those features such as a fast response speed andelectrical controllability, a study of superimposing a signal on anilluminative LED light and thereby transferring the signal has beenconducted.

Lighting elements are often provided on the ceiling or a wall surface,or a pole is set up to irradiate a certain area from above, therebypreventing generation of a shadow. Typically, wireless communicationincluding optical communication has a problem of shadowing which causesdecrease in signal intensity and disturbance in communication behind anobject. However, since lighting elements are often provided so as toprevent shadowing as described above, this means that illuminative lightcommunication is possible without development of shadowing. In addition,there is an advantage that high communication quality is ensured using ahigh electric power for lighting.

However, use of illuminative light develops a problem that illuminativelight communication cannot be carried out without lighting. Lights maybe kept on even when unnecessary. However, users may not appreciatekeeping lights turned on when unnecessary in view of energyconservation, or lighting may be prohibited at night, for example. Thereis a problem that communication cannot be carried out without lightingand cannot be carried out when unattended, at night, or while using aprojector.

On the other hand, infrared light communication has been widely used,and standardization has been carried out by the infrared dataassociation (IrDA) or the like. There is fear that infrared lightcommunication may adversely influence the human body such as eyes. As aresult, it is impossible to carry out high electric power communication.In addition, it is characterized in that it is easily influenced byshadowing, which causes decrease in communication quality due tocharacteristics of light when an obstruction such as a user exists. Fromthese reasons, an available range is limited, and that communication maynot be stably carried out.

To solve such problems, a communication device with the followingstructure uses illuminative light and infrared light together and isavailable even without lighting.

FIG. 1 is a block diagram of an illuminative light communication device,according to a first embodiment of the present invention. In thedrawing, 311 denotes an optical modulator, 312 through 314 denoteswitches, 315 denotes an electric power divider, 316 denotes a lightingunit, 317 denotes a communicating unit, 321 denotes a data terminal, and322 denotes a light receiving unit. A light source which emits light forlighting is provided in the lighting unit 316. Since a semiconductorlight emitting element capable of operating at a fast response speedsuch as a white LED is used as a light source, illuminative lightcommunication is possible by controlling blinking and/or lightintensity. In addition, the communicating unit 317 may transmit datausing an optical communication method other than illuminative lightcommunication such as infrared light communication. Note that thelighting unit 316 and the communicating unit 317 may be deployed in thesame device to be described later. Needless to say, those may be formedseparately.

The optical modulator 311 and the electric power divider 315, which areused as a modulation means according to the present invention, modulateilluminative light by controlling blinking and/or light intensity of thelighting unit 316 in conformity with data. In this exemplary structure,the optical modulator 311 modulates received data using a predeterminedmodulation method, superimposes the resulting modulated data on anelectric power waveform, and then transmits the resulting superimposeddata waveform to the electric power divider 315 via the switch 313 or tothe communicating unit 317 via the switch 314. This allows control oflight intensity and on/off control of the lighting unit 316 and thecommunicating unit 317.

The electric power divider 315 mainly supplies electric power to thelighting unit 316. When an electric power superimposed with modulateddata to be transmitted from the optical modulator 311 via the switch 313is supplied, this electric power is supplied to the lighting unit 316.

The switches 312 through 314, which are switching means of the presentinvention, are turned on or off in conformity with an external commandfor turning on or off. The switch 312 allows or prohibits electric powersupply to the electric power divider 315, thereby turning lights on oroff. The switch 313 allows or prohibits provision of the modulated datato the electric power divider 315, thereby allowing or prohibitingtransmission of data via illuminative light (illuminative lightcommunication) while the lighting unit 316 is illuminating. The switch314 allows or prohibits transmission of the modulated data to thecommunicating unit 317. Note that either the switch 312 or the switch313 is turned on or both of them are turned off at the same time.

FIG. 2 is a table describing exemplary operations defined according torespective combinations of an on and an off status of the switches 312through 314. When the switch 312 is on, the switch 313 is off, and theswitch 314 is on, the communicating unit 317 carries out communicationwhile the lighting unit 316 is illuminating as shown in FIG. 2 (1). Notethat in FIG. 2, communication by the communicating unit 317 is describedas ‘infrared light communication’, but the present invention is notlimited to this. When setting of the switches 312 and 313 is the same asthat just described, and the switch is off, only lighting is carried outwithout carrying out communication as shown in FIG. 2 (2). In this case,illuminative light is not used for communication. When the switch 312 isoff, the switch 313 is on, and the switch 314 is on, as shown in FIG. 2(3), the lighting unit 316 carries out lighting and illuminative lightcommunication, and the communicating unit 317 also carries out datacommunication. In this configuration, when the switch 314 is off, thelighting unit 316 carries out lighting and illuminative lightcommunication as shown in FIG. 2 (4). When both switches 312 and 313 areoff, the lighting unit 316 is not used. In this configuration, when theswitch 314 is on, the communicating unit 317 carries out datacommunication as shown in FIG. 2 (5). Otherwise, when the switch 314 isoff, neither lighting nor communication is carried out as shown in FIG.2 (6).

For example, in the case of carrying out communication when lighting isneeded, data communication by the communicating unit 317 or illuminativelight communication by the lighting unit 316 may be carried out byturning the switch 312 on, the switch 313 off, and the switch 314 on asshown in FIG. 2 (1), or turning the switch 312 off, the switch 313 on,and the switch 314 either on or off as shown in FIG. 2 (3) or FIG. 2(4). On the other hand, when lighting is unnecessary, data communicationby the communicating unit 317 is carried out by turning both switches312 and 313 off, and the switch 314 on as shown in FIG. 2 (5).

As described above, illuminative light communication with lighting ispossible, and communication without lighting is also possible. Wheninfrared light communication is used as a communication method for thecommunicating unit 317 as described above, since infrared light isinvisible, a person cannot sense the brightness during communication.Therefore, communication can be carried out even without lighting.

FIG. 3 is a schematic diagram of an exemplary lighting element,according to the present invention, which is preferable to be used forthe illuminative light communication device, according to the presentinvention. FIG. 4 is a diagram describing an exemplary application ofthe lighting element, according to the present invention, to theilluminative light communication device, according to the presentinvention. In the drawing, the same symbols are given to the same partsas those in FIG. 8, and repetitive descriptions thereof are thusomitted. 335 denotes an infrared light emitting element. As shown inFIG. 8, needless to say, typical LEDs for lighting emit only visiblelights, and do not emit infrared light. Accordingly, in the case ofcarrying out infrared light communication by the communicating unit 317as described above, an infrared light LED must be additionally providedas the communicating unit 317. Needless to say, different LEDs may beused in the lighting unit 316 and the communicating unit 317.Alternatively, since both LEDs have similar structures, they can beintegrated into one. An example of this case is shown in FIG. 3.

In the example shown in FIG. 3, the infrared light emitting element 335is provided in an LED which emits white light by mixing red, green, andblue emitted lights as shown in FIG. 8A. Even though the infrared lightemitting element 335 is provided in this manner, the package size isseveral millimeters wide and several millimeters high, which is almostthe same as that of typical LEDs.

To use such lighting element in an illuminative light communicationdevice, as shown in FIG. 4, the red light emitting element 332, thegreen light emitting element 333, and the blue light emitting element334 are electrically connected to the electric power divider 315 so asto receive electric power with lighting or modulated electric powerduring illuminative light communication. In addition, the infrared lightemitting element 335 is connected to the optical modulator 311 via theswitch 314, allowing the optical modulator 311 to modulate and drive theinfrared light emitting element 335 when the switch 314 is turned on.Furthermore, a shared electrode may be grounded along with the opticalmodulator 311 and the electric power divider 315.

For ordinary lighting, a visible white illuminative light is emitted bymixing three color lights emitted from the red light emitting element332, the green light emitting element 333, and the blue light emittingelement 334. High-speed modulation of this illuminative light allowsilluminative light communication. In addition, light emitted from theinfrared light emitting element 335 is invisible. However, high-speedmodulation of light to be emitted allows wireless communication usinginvisible infrared light.

As described above, illuminative light communication by carrying outhigh-speed modulation of respective lights emitted from the red lightemitting element 332, the green light emitting element 333, and the bluelight emitting element 334, and infrared light communication by carryingout high-speed modulation of light emitted from the infrared lightemitting element 335 can be changed over by changing settings of theswitches 312 through 314 as described above. For example, when bothlighting and communication are required, the red light emitting element332, the green light emitting element 333, and the blue light emittingelement 334 are operated to emit respective lights, and at the same timethe emitted lights are modulated at a high speed, thereby transmittingdata. As a result, since an optical power needed for lighting may alsobe used for communication, high-speed and high-quality communication canbe carried out. In addition, when lighting is unnecessary butcommunication is required, communication is carried out by modulatingand driving the infrared light emitting element 335 and operating it toemit infrared light. In this case, since infrared light is invisible,communication can be carried out even without lighting. In addition,typically, since people are often absent when lights are off, adverseinfluences on the human body such as eyes can be decreased.

Needless to say, infrared light communication may also be carried outwith lighting, by modulating and driving the infrared light emittingelement 335. In this case, what should be done on a receiver side is toreceive only infrared light, and there is no need to deal with multiplewavelengths, allowing provision of a simplified structure.

Alternatively, communication using both illuminative light and infraredlight may be carried out by modulating and driving respective lightsfrom the red light emitting element 332, the green light emittingelement 333, the blue light emitting element 334, and also modulatingand driving light from the infrared light emitting element 335. In thiscase, since all power is available, higher-speed and higher-qualitycommunication than that using the aforementioned methods is possible.

Note that since the red light emitting element 332, the green lightemitting element 333, the blue light emitting element 334, and theinfrared light emitting element 335 in the configuration shown in FIG. 3may be driven independently, multiple pieces of data can be transmittedat the same time by dividing wavelengths.

FIG. 5 is a schematic diagram of another exemplary lighting element,according to the present invention, which is preferable to be used forthe illuminative light communication device according to the presentinvention. FIG. 6 is a diagram describing another application of anexemplary lighting element, according to the present invention, to theilluminative light communication device according to the presentinvention. In the drawing, the same symbols are given to the same partsas those in FIG. 8, and repetitive descriptions thereof are thusomitted. 344 denotes an infrared light emitting element. In the exampleshown in FIG. 5, the infrared light emitting element 344 is provided inthe LED device 341 structured as shown in FIG. 8B.

To use such a lighting element in the illuminative light communicationdevice, as shown in FIG. 6, the light emitting element 342 iselectrically connected to the electric power divider 315 and receiveselectric power with lighting, and receives modulated power duringilluminative light communication. In addition, the infrared lightemitting element 335 is electrically connected to the optical modulator311 via the switch 314, allowing the optical modulator 311 to modulateand drive the infrared light emitting element 335 while the switch 314is turned on. Furthermore, a shared electrode may be grounded along withthe optical modulator 311 and the electric power divider 315.

For ordinary lighting, white light is emitted by irradiating thefluorescer 343 with blue light or ultraviolet light emitted from thelight emitting element 342. In this case, illuminative light can be usedfor communication by carrying out high-speed modulation and driving thelight emitting element 342. In addition, modulation and driving of theinfrared light emitting element 344 allow wireless communication usinginvisible infrared light.

As with the example shown in FIG. 3, when both lighting andcommunication are required, modulation and driving of the light emittingelement 342 are carried out, thereby transmitting data. As a result,since optical power needed for lighting can also be used forcommunication, high-speed and high-quality communication can be carriedout. In addition, when lighting is unnecessary but communication isrequired, communication is carried out by modulating and driving theinfrared light emitting element 335 to emit infrared light. In thiscase, since infrared light is invisible, communication can be carriedout without lighting. In addition, typically, since people are oftenabsent when lights are off, adverse influences on the human body such aseyes can be decreased.

Needless to say, as with the example shown in FIG. 3, with lighting,infrared light communication may be carried out by modulating anddriving the infrared light emitting element 344, or by modulating anddriving both the light emitting element 342 and the infrared lightemitting element 344. Note that according to the configuration shown inFIG. 5, it is possible to transmit different pieces of data in parallelby driving the light emitting element 342 and the infrared lightemitting element 344 individually, however, it is impossible to transmitdifferent pieces of data via a red, a green, and a blue illuminativelight wavelength, respectively.

FIG. 7 is a block diagram of an illuminative light communication device,according to a second embodiment of the present invention. Symbols inthe drawing are the same as those in FIG. 1. According to theaforementioned first embodiment, communication without lighting iscarried out by the communicating unit 317, which is additionallyprovided. In the second embodiment, an example where communication iscarried out by a lighting unit 316 without a communicating unit 317without lighting is shown.

In this exemplary structure, a switch 312 is used for turning lights onor off while a switch 313 is used for changing over between carrying outand not carrying out communication.

An electric power divider 315 drives the lighting unit 316 in accordancewith the statuses of the respective switches 312 and 313. It carries outoptical communication by modulating in accordance with data to betransmitted while supplying electric power sufficient for lighting tothe lighting unit 316. On the other hand, it carries out communicationwithout lighting by modulation-controlling in conformity with data to betransmitted so as to make the lighting unit 316 blink a necessary numberof times for communication.

For example, when the switches 312 and 313 are turned on, illuminativelight communication is carried out through modulation while the lightingunit 316 is illuminating. In addition, when the switch 312 is turned offand the switch 313 is turned on, communication is carried out by drivingthe lighting unit 316 in conformity with a modulation signal from anoptical modulator 311, and making the lighting unit 316 emit for a shorttime in conformity with data to be transmitted. Short time lightemission is unperceivable. Accordingly, even when light is actuallyemitted, it appears to the human eye as if not illuminating, therebyallowing carrying out communication even when not illuminating. Notethat when the switch 312 is turned on and the switch 313 is turned off,ordinary lighting is carried out; otherwise, when both the switches 312and 313 are turned off, communication is not carried out withoutlighting.

In this manner, since without lighting, the lighting unit 316 iscontrolled not to continuously illuminate, but is allowed to illuminatefor a short time in conformity with data, visible light communicationcan be carried out by the lighting unit 316 while it appears to thehuman eye as if not illuminating.

As described above, other than communication through short time lightemission, communication by making the lighting unit 316 emit a lowintensity of light that allows communication is possible. In this case,without lighting, communication is often possible as long as lighting isnot completely prohibited, or illuminating with almost the sameintensity as that provided by a safety lamp.

As described above, the present invention allows provision of anilluminative light communication device capable of carrying outcommunication even without lighting, and also provision of a lightingelement preferable to be used for the illuminative light communicationdevice.

An illuminating facility may be available around the clock, orotherwise, may not illuminate while unattended, while surrounded bysunlight or while using a projector. An attempt of data transmissionusing only illuminative light in such a case develops a problem thatlighting is required as data is transmitted. The present inventionallows communication even without lighting by carrying out infraredlight communication without lighting, or by using a low light intensityfor short-time communication.

In addition, in the case of using infrared light communication,provision of a lighting element integrally made up of an illuminativelight emitting element and an infrared light emitting element allowsinfrared light communication without lighting, as described above.Furthermore, lights ranging from visible light to infrared light can beemitted by an integrated element, which allows decrease in device size.In other words, rather than using an independent lighting system and anindependent infrared data communication system, a new compact systemstructured by integrating lighting elements can be provided. From adifferent point of view, wireless infrared light data communication hasbeen well-known, but it has been structured regardless of lighting. Inother words, a transmitter/receiver unit other than a lighting unit isfixed to the ceiling. Therefore, it is often difficult to fix it acrossa large area of the ceiling, and an adverse influence of shadowing orthe like may prevent utilization thereof. However, use of the lightingelements, according to the present invention, allows easy integration ofan infrared light data communication system and a lighting system. Sincelighting units are typically fixed to a large area of the ceiling or thelike, the lighting elements, according to the present invention, can beeasily fixed to the large area for data communication. As a result, anadverse influence of shadowing is decreased, and reliable wirelessinfrared light communication can be provided.

1. An illuminative light communication device, comprising: a lightingunit that emits light for lighting; a modulator that controls blinkingor light intensity of the lighting unit in accordance with data, therebymodulating the emitted light; a communicating unit that transmits thedata through optical communication other than illuminative lightcommunication; and a switching unit that changes over respectiveoperations of the modulator and the communicating unit based on whetherthe lighting unit is on or off; wherein the switching unit changes oversuch that the communicating unit can operate while the lighting unit isoff.
 2. The illuminative light communication device according to claim1, wherein the communicating unit transmits data through infrared lightcommunication.
 3. The illuminative light communication device accordingto claim 2, wherein: the lighting unit comprises a plurality of LEDdevices; the LED devices comprise an infrared light emitting device thatcan selectively emit infrared light; and the infrared light emittingdevice is used as the communicating unit.
 4. An illuminative lightcommunication device, comprising: a lighting unit that emits light forlighting; and a modulator that controls blinking or light intensity ofthe lighting unit in accordance with data, thereby modulating theemitted light; wherein in response to an on-switching instruction, themodulator modulate in accordance with the data while supplyingsufficient electric power for lighting to the lighting unit, while inresponse to an off-switching instruction, the modulator modulate inaccordance with the data to allow the lighting unit to blink a number oftimes necessary for communication.
 5. A lighting device for emittingilluminative light, comprising: an illuminative light emitting devicethat emits white light for lighting; and an infrared light emittingdevice that emits infrared light for infrared data communication.
 6. Thelighting device according to claim 5, wherein the illuminative lightemitting device is controlled for modulation to carry out illuminativelight communication independently of the infrared light emitting device.7. The lighting device according to claim 5, wherein the illuminativelight emitting device comprises a red, a blue, and a green lightemitting device, and the infrared light emitting device is arrangedalong with each light emitting device.
 8. The lighting device accordingto claim 5, wherein the illuminative light emitting device comprises ablue or an ultraviolet light emitting device and fluorescer that isprovided surrounding the light emitting device.